I've finally decided to change the format of my "weekly" blogs... given that I've probably repeated myself several times on many subjects I've decided to slow things down and only report on things in the news. I've been stirred into writing a new entry by the UKMA's (UK Metric Association) press release detailing their latest comments on road metrication.

It was originally intended that British roads would be fully metricated during the 1970's however this was postponed, initially due to cost but then using the excuse that not enough people in Britain understood metric for it to be safe (disproved by all of the other British Commonwealth countries that did it with no safety issues). In recent years this excuse has fell by the wayside, cost now being the primary concern (disproved by the recent completion by Ireland as well as methods used in Canada). We now also have the added problem of a reactionary media peddling lies about how much it will cost and how bad it will be for Britain if we switch.

So, what went wrong?

Lets start with a 2005 Freedom of Information request which unearthed a January 1989 memo about metrication costs. Unfortunately the memo concentrates on the fact that conversion might be "messy" and would bring little economic benefit, clearly ignoring potential cost savings in education and road safetyof completing metrication, something that road metrication would go a long way towards doing. The technical issues raised by the memo can actually be used to show that costs need not be high for metrication.

Page one section 2 of the note starts off by stating that "The present policy is that all height restriction signs should eventually include both imperial and metric dimensions" and then goes on to speak about width and length signs, stating that these could be replaced under normal maintenance/renewal cycles. So, why was this not done? We could have had 100% dual-unit height, width and length signs by the mid 1990's at little cost to the taxpayer.

The same section mentions that  "tons" have already been replaced by "tonnes".

Section 3 goes on to talk about replacing yard with metre and states explicitly that, as far as the author is concerned (and this is borne out by more recent DfT documents) that, on the roads, 1 yard is the same as 1 metre. It states that signs showing distances in yards could be very easilly replaced by their metric equivalent.

Then comes the rub... many signs, it says, use "m" to refer to "miles", however it goes on in section 4 to say "The next round of consultation on traffic sign regulations (a Statutory Instrument) proposes to remove this anomaly by dropping the miles reference" and finishes with "and remove the potential confusion with metres".

So, we have several simple actions based on this.

• Make the use of metric on height, width and length signs mandatory.
• Ban the use of "m" to mean "miles"
• Replace variations of "yard" with "m" and "metre" (phased in once "m" for "miles" is worked out of the system). 

Based on this, with exception to the mile, all British road signs would have been metric by the mid to late 1990's. This would have cost the taxpayer little or nothing to achieve.

So, what happened? The proposed changes to traffic signs regulations never occured... except a clause was added specifically prohibiting the use of metres on distance signs. In addition to this, despite the fact that a letter was sent out to all local and regional authorities in May 1991 telling them "With effect from 1 January 1990, a number of signs showing weights in imperial tons and relating to unladen vehicle weights may no longer be used, and have become un-enforceable" there are still (probably) hundreds of these signs still in existence (I run out of fingers counting the number in Peterborough alone). Despite this, authorities are actively ignoring legal requirements on these signs and even the Highways Agency is ignoring advice that height and width signs should be dual-unit where possible!

The DfT is currently running a consultation on road safety and is planning a consultation on changes to Traffic Signs General Regulations and Directions (TSGRD). There are very few changes they need to make in order to clean up this mess.

• Make the use of metric on height, width and length signs mandatory, make the use of imperial optional. The latter change would allow the continuing use of imperial units by those who seem to think it's justified. Within 3 years imperial-only signs should have disapeared and there would likely be decreasing use of dual-unit signs.
• Ban the use of "m" for "miles". This could be done by either 1) plating over the "m" or 2) replacing the "m" with "mi" as is used in the USA. Moving forward, shorter distances (such as fractions of a mile) could be replaced with 1000's of metres:
  • ¼m would become 400 m
  • ½m would become 800 m
  • 1m would become 1600 m
• Make the use of the metre legal on all road signs and allow it as an alternative to yards.
• Publish a leaflet to be delivered with car tax renewals pointing out that "m" means metres... but probably also clarifying the obvious that "1 m" is not 1 metre!

Assuming TSGRD were re-published in 2010 with these changes, British roads could be completely devoid of feet and inches by 2015 at the very latest.

In addition, I believe TSGRD also needs the following changes:

• "t" for tonne is already optional, it should be made mandatory hence phasing out the use of "T". The use of "ton" should also be specifically prohibited.
• Use of km and km/h on road signs should be made legal and designs for km distance signs added.

Clearly speed limits need to be dealt with separatly, but there is no reason why distance signs should not be included. Even with a longer term changeover there is no reason why Britain could not have almost all distance signs in km by the end of the next decade. There is also no reason why historical signs and markers/mileposts showing miles cannot remain in place alongside their metric equivalents.

Ironically, the USA have shown us the way forward in the fact that some of their roads have metric distance and speed signs; granted, in some places these are being replaced by mile-only signs. However the news this year that a 100 km fully metric stretch of road in Arizona is to be converted to miles has not gone down too well with many local residents and businesses who are saying that converting to miles is a waste of money! If Americans aren't confused by dual units on their road signs then why should we be?